Should I install an immersion heater?

retiredin2011

I have Johnston and Starley warm air heating with a Janus water heater to heat my hot water tank.

I also have a power shower which uses this hot water.

I don't have an immersion heater.

I've just had my heating serviced and have been informed that although the warm air heating is OK and parts are available that the hot water heater is getting to the end of its life and parts may not be available for it and it may need to be replaced.

It would have to be a separate water heater as it would not fit in the warm air unit, so I have been told.

Also because it is not condensing and has a pilot light it is supposedly inefficient although during the summer when my heating is off I (only?) use 18 kWh of gas a day for hot water and cooking.

Which, given the cost of my gas, works out about £285 a year, this includes the standing charge.

I was just wondering if it would be cheaper for me to install and use an immersion heater instead of replacing the water heater when it finally gives up?

I have a relative who is a plumber so it would only cost the price of the immersion and 500 gms of tobacco to fit, when he has the time.

I could also replace my power shower for an electric shower but given the difference in water pressure I would prefer to keep my power shower.

So how much electricity would I use if I had an immersion?

The hot water tank needs about 2 kWh a day of gas to maintain its temperature, found this out when I went on holiday and forgot to turn off the water heater.- and out of the 18 kWh a day gas usage the pilot light uses 3 kWh of gas, I have no idea how much gas the cooker uses but there is only 2 of us in the house.

The heating and water heater are 22 years old

macman

Immersion heaters are usually used on an E7 tariff to heat the hot water cheaply overnight. Heating it on a single rate tariff is about 300% more per kWh than using gas.

HappyMJ

retiredin2011 wrote: »

I have Johnston and Starley warm air heating with a Janus water heater to heat my hot water tank.

I also have a power shower which uses this hot water.

I don't have an immersion heater.

I've just had my heating serviced and have been informed that although the warm air heating is OK and parts are available that the hot water heater is getting to the end of its life and parts may not be available for it and it may need to be replaced.

It would have to be a separate water heater as it would not fit in the warm air unit, so I have been told.

Also because it is not condensing and has a pilot light it is supposedly inefficient although during the summer when my heating is off I (only?) use 18 kWh of gas a day for hot water and cooking.

Which, given the cost of my gas, works out about £285 a year, this includes the standing charge.

I was just wondering if it would be cheaper for me to install and use an immersion heater instead of replacing the water heater when it finally gives up?

I have a relative who is a plumber so it would only cost the price of the immersion and 500 gms of tobacco to fit, when he has the time.

I could also replace my power shower for an electric shower but given the difference in water pressure I would prefer to keep my power shower.

So how much electricity would I use if I had an immersion?

The hot water tank needs about 2 kWh a day of gas to maintain its temperature, found this out when I went on holiday and forgot to turn off the water heater.- and out of the 18 kWh a day gas usage the pilot light uses 3 kWh of gas, I have no idea how much gas the cooker uses but there is only 2 of us in the house.

The heating and water heater are 22 years old

My opinion...it's cheaper to have an electric immersion heater and turn the Janus water heater off saving the wasted gas each day running the pilot light and just having the immersion heater run overnight on an Economy 7 tariff heating your water. It will be cheaper than the cost of gas and the cost of replacing the Janus water heater. A gas cooker does not use much gas.

retiredin2011

I don't have economy 7 and would that not be overkill just for an immersion?

Errata

macman wrote: »

Immersion heaters are usually used on an E7 tariff to heat the hot water cheaply overnight. Heating it on a single rate tariff is about 300% more per kWh than using gas.

Mine isn't, and I've never had one in any of my previous properties that was.

HappyMJ

retiredin2011 wrote: »

I don't have economy 7 and would that not be overkill just for an immersion?

Not really. Economy 7 is designed for immersion heaters which use a fairly significant amount of electricity to heat a cylinder. If you aren't going to use it on Economy 7 it won't be worth it if you have a gas supply.

retiredin2011

It would, I hope, still be a lot less than the cost of getting a new gas water heater.

Would a tank of hot water heated by an immersion supply enough hot water for a couple of 10 min power showers?

simongregson

You can buy replacement janus water heaters from johnson and starley.

macman

retiredin2011 wrote: »

It would, I hope, still be a lot less than the cost of getting a new gas water heater.

Would a tank of hot water heated by an immersion supply enough hot water for a couple of 10 min power showers?

Not in the long term, because you'll be paying approx 300% more per kWh to heat by standard rate electricity, compared to gas.

Richie-from-the-Boro

The Janus water, and the 'Johnson and Starley' gas warm air space heating system it is married with, is still .. .. three or four decades later, a very efficient space and water heating system. Warm air heating output is nearly instantaneous, zero incidence of the water leaks, sticking valves, sludge, pumps, etc. than can develop with ordinary systems, they typically already have a 5 or 6 times longer service life than water based systems. If you have one of these systems you are unlikely to have, or ever benefit from E7. If you have need for a shower and the header to accommodate the shower volume delivery needs, you already have cheap shower water. A full replacement blown warm air type for type can be had that provide mains pressure hot water showering, wet rads into a new build extension you can even bolt on a Multicalor MC, the choices are endless.

In a sentence, if you already have a 'Johnson & Starley with Janis' keep it

Don't let BG salesman and others frighten you, these systems are very well regarded in the industry by gas fitters and 35 years later are still delivering cheap [relative to leccy] water. As regards modern gas - [STRIKE]with a combi.[/STRIKE] try doing that ! - with a modern combi.